在實際中用到Mysql的更新操作，以備後用

mysql數據庫，表shunxu，字段：id，uid，cid，instime，orderID

更新操作要求：對uid分組，instime排序，在orderID字段裏寫入順序號，sql語句

SET @C = 0;

SET @A = 0;

UPDATE shunxu SET orderID = ( SELECT CASE WHEN @A = uid THEN @C := @C + 1 ELSE (@C := @C + 1 AND @A := uid) END ) ORDER BY uid,instime

結果如下：

uid	cid	instime	id	orderID
240	7759	1478140136	10	1
240	7775	1478832114	12	2
245	7778	1478854702	33	1
331	7779	1477552073	21	1